CVE-2021-22241 in Community Edition
Summary
by MITRE • 08/06/2021
An issue has been discovered in GitLab CE/EE affecting all versions starting from 14.0. It was possible to exploit a stored cross-site-scripting via a specifically crafted default branch name.
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Analysis
by VulDB Data Team • 08/10/2021
The vulnerability identified as CVE-2021-22241 represents a critical stored cross-site scripting flaw within GitLab Community and Enterprise editions. This security issue affects all versions beginning with 14.0, making it a widespread concern for organizations utilizing GitLab for their version control and collaboration needs. The flaw manifests through a specifically crafted default branch name that, when stored in the system, can execute malicious scripts in the context of a victim's browser session.
The technical exploitation of this vulnerability occurs through the manipulation of default branch naming conventions within GitLab repositories. When an attacker creates a repository with a maliciously crafted branch name containing embedded script payloads, these scripts become persistent within the system's database. Upon subsequent access to repository information or branch listing pages, the stored malicious code executes in the browser context of any user viewing the affected repository details. This stored XSS vulnerability operates at the application layer and specifically targets the web interface components responsible for rendering branch names and repository metadata.
The operational impact of CVE-2021-22241 extends beyond simple script execution, as it can potentially enable attackers to escalate privileges, steal session cookies, perform unauthorized actions on behalf of users, or redirect victims to malicious sites. The vulnerability's persistence through stored data means that once exploited, the malicious scripts remain active until the affected branch name is modified or removed from the system. This characteristic makes the vulnerability particularly dangerous in environments where multiple users regularly access repository information, as the attack surface expands with each user interaction.
Organizations utilizing GitLab should prioritize immediate remediation through the application of security patches released by GitLab, as this vulnerability has been classified with high severity according to industry standards. The flaw aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities, and follows attack patterns documented in the MITRE ATT&CK framework under the technique of web application attacks. Security teams should implement monitoring for anomalous branch naming patterns and conduct thorough review of repository configurations to identify any potential exploitation attempts. The vulnerability demonstrates the critical importance of input validation and output encoding in web applications, particularly when handling user-generated content that may be displayed in subsequent user interfaces.